The present invention relates to a method of constructing field-effect transistors (FETs), particularly but not exclusively, metal oxide semiconductor transistors (MOSTs) which can be constructed as either single polarity devices or as complementary devices (CMOS) to operate in high performance integrated circuits or as discrete devices.
A type of MOST which has many advantages is one in which the source and drain regions and the region separating the source and drain regions are formed in silicon deposited on sapphire, this structure being known as silicon on sapphire (SOS) (See "Sapphire Brings Out the Best in CMOS" by S. Sheffield Eaton, Electronics, June 12th 1975, page 115). However such devices are expensive to manufacture since sapphire is required as a starting material and suffer from the disadvantage that high leakage currents flow between the source and drain because of crystal distortion at the interface where during manufacture silicon is grown on a sapphire crystal.